Asparagirl makes a good point about Germany's suggestion that Jews don't wear anything that brings attention to the fact that they are Jewish.
Such a request isn't too much different to the prevailing belief that women shouldn't be out alone at night, and definitely shouldn't be out alone at night in the " wrong kind of clothing " . These suggestions are an admission by law enforcement that they are unable to protect their citizens from harm all of the time. Of course this is true, but once such 'practical advice' gets out in to the ether, it almost becomes a moral imperative - any victim who failed to follow such dictates is somehow at fault.
